SUROBI, Afghanistan, Aug. 20 — The conversation at a little restaurant here began politely, as many do in Afghanistan when the subject is the Americans. A shopkeeper said he had never seen an American soldier but felt they had come to help. A cook said the Americans' presence was all that kept the country quiet. Then a village leader, known as Khairullah, spoke up. "Afghanistan has no need for foreign troops," he said firmly. "We need national unity. We need friendship between ethnic groups. We don't need an invasion." It is rare for Afghans to talk so openly against the...